This invention relates to an improved engine unit for a vehicle and more particularly to an improved compact internal combustion engine, transmission and final drive assembly for a vehicle.
The difficulty in providing a compact yet serviceable drive arrangement for a motor vehicle are well known. These problems are particularly acute in conjunction with front wheel drive vehicles, although similar problems are present in rear engine, rear wheel drive vehicles. In order to minimize some of the spatial problems and offset some of the deficiencies in that type of vehicle, it has been proposed to mount the powering engine in a transverse relationship so that its output shaft rotates about an axis that extends transversely to the vehicle. Such arrangements are very popular due to the degree of compaction which they afford without significantly adversely effecting serviceability.
However, it is the normal practice to put the transmission and final drive together on one side of the engine. This means that the engine must assume a relatively upright position in order to accommodate these driving components. Such an upright arrangement can give rise to sacrifices in the configuration of the body of the vehicle. For example, in a front engine, front wheel drive arrangement, such a placement causes the engine to be put in either a vertical or a forwardly inclined position. As such, the height of the engine is relatively high at the front of the vehicle and streamlined hood shapes are not possible. Similar problems also occur at the rear end of the vehicle in connection with rear engine, rear wheel drive applications. In addition to the difficulties in providing the desired configuration for the vehicle body structure, the location of the induction and exhaust systems in such applications becomes quite difficult.
It is, therefore, a principal object of this invention to provide an improved layout for the engine transmission final drive of a motor vehicle.
It is a further object of this invention to provide an improved transverse engine, transmission, final drive layout for a motor vehicle.
It is a yet further object of this invention to provide an improved, compact and relatively low engine drive arrangement for a front wheel drive vehicle.
In connection with the use of transverse engines, it has been previously noted that it is the frequent practice to position the transmission and final drive at one side of the engine. As has been noted, this tends to cause the engine to be more upright than might otherwise be desirable. In addition, the positioning of both the transmission and final drive at one side of the engine can compromise the position of the engine relative to the driven axle. Where, however, the engine is positioned centrally and the transmission is on one side and the final drive is on the other side, an arrangement may result that provides too great an overall length (when the engine is considered transversely) or width (when the engine is considered longitudinally).
It is, therefore, a still further object of this invention to provide an improved compact engine transmission, final drive for a motor vehicle.
It is a yet further object of this invention to provide an improved compact power unit for a motor unit for a motor vehicle wherein the engine is positioned centrally with the transmission on one side and the final drive on the opposite side.
In addition to providing a compact arrangement in the fore and aft direction in connection with the use of transverse engines, it is also desirable to maintain the overall length of the engine as short as possible. Of course, this holds true with both fore and aft and transverse engines. One way in which the length of an engine can be reduced is by driving an auxiliary shaft from the crankshaft and taking the final drive and camshaft drive off of this auxiliary shaft. In this arrangement, the camshaft drive can be located inwardly from the ends of the engine and will not unduly lengthen the engine. However, where both the final drive and the camshaft drive are taken off of the same auxiliary shaft, certain problems are encountered. For example, there is some desirability in providing a torsional damper in the output shaft of the engine. However, the camshaft drive cannot be driven through such a torsional damper because the cam timing events will vary during engine revolution.
It is, therefore, a yet further object of this invention to provide an improved and compact drive arrangement wherein both the camshaft and output are taken off an auxiliary shaft and wherein a vibration damper is provided in only one of the outputs.
It is a further object of this invention to provide an improved camshaft and final drive from an auxiliary shaft of an engine wherein the final drive has a torsional damper but the camshaft drive does not.
In conjuction with engine design, it is normally the practice to employ a torsional vibration damper at one end of the engine. Normally this torsional vibration damper is driven from the crankshaft at the end opposite that at which the flywheel is driven. Such an arrangement, of course, lengthens the crankshaft and, accordingly, the overall engine.
It is, therefore, a still further object of this invention to provide an improved arrangement for providing a torsional vibration damper for a crankshaft without lengthening the overall engine construction.
It is a further object of this invention to provide an improved drive arrangement for an engine wherein the use of a torsional damper does not add significantly to the length of the engine.
As has been previously noted, one way in which the overall length of an engine can be reduced is by driving the camshaft from an auxiliary shaft that is driven from the engine crankshaft at a point between its ends. However, if a separate gear is affixed to the crankshaft for driving the timing chain drive shaft, the full advantages of shortening of the crankshaft cannto be achieved.
Therefore, it is yet a further object of this invention to provide an improved and compact power takeoff arrangement for the crankshaft of an internal combustion engine that facilitates shortening of its length without sacrificing its functions.
As has been noted, in connection with the provision of transverse engines for front wheel drive vehicles, it is important to insure that the engine is located and oriented in such a way that a relatively low hood line will result. It is, therefore, a still further object of this invention to provide an improved engine orientation for a transverse engine, front wheel drive vehicle wherein the engine cylinders are inclined in such a way as to provide a low hood line.
It is a further object of this invention to provide a rearwardly inclined, transverse engine for a front wheel drive vehicle.
In the event an engine of a transverse disposition is formed with rearwardly inclined cylinder bores, the cylinder block casting can have a configuration which is difficult to form. That is, it is the normal practice to have the lower end of the cylinder block in mating relationship with the upper end of the crankcase. If a horizontally disposed upper crankcase surface is employed, this means that the cylinder block lower surface must be similarly oriented, which can present problems in connection with the use of rearwardly inclined cylinders.
It is, therefore, a still further object of this invention to provide an improved cylinder block crankcase arrangement wherein the cylinder block has inclined cylinder bores and the cylinder block and crankcase have mating surfaces.
In connection with engines having inclined cylinder blocks, there is also the problem of location and placement of the manifolding for the engine. If the engine is inclined rearwardly, it is desirable to place the intake manifold on the forward side of the engine for serviceability and other reasons. However, when the intake manifold is located forwardly, the manifold and associated components can, themselves, further encroach upon the hood line of the vehicle.
It is, therefore, a still further object of this invention to provide an improved arrangement and configuration for the intake manifold and induction system of a transverse engine having rearwardly inclined cylinders.